# Google Gemini SynthID Text Watermark Tool (`rainminer/google-gemini-watermark-checker`) Actor

Paste text or upload PDF and DOCX to check whether writing is AI generated. Looks for Google SynthID-Text signals when the sample is long enough and returns isAiGenerated, confidence, likely source, and limitations as JSON. For editors, reviewers, and trust-and-safety teams. No Google login.

- **URL**: https://apify.com/rainminer/google-gemini-watermark-checker.md
- **Developed by:** [rainminer](https://apify.com/rainminer) (community)
- **Categories:** AI, Developer tools
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $5.00 / 1,000 text checkeds

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.

Learn more: https://docs.apify.com/actors/running/actors-in-store.md#pay-per-event

## What's an Apify Actor?

Actors are web data automations that power AI and operations. They run on the Apify platform to scrape websites, process data, connect APIs, and automate workflows.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.
Actors are written with capital "A".

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.
The best way to integrate Actors is as follows.

- **AI agents and MCP clients** — the [Apify MCP server](https://docs.apify.com/integrations/mcp.md) at `https://mcp.apify.com` (remote, streamable HTTP, OAuth on first use).
- **Agentic workflows and local Actor development** — [Agent Skills](https://apify.com/.well-known/agent-skills/index.json) with the [Apify CLI](https://docs.apify.com/cli/docs.md): `npm install -g apify-cli`, then `apify login`.
- **JavaScript/TypeScript projects** — the official [JS/TS client](https://docs.apify.com/api/client/js/docs.md): `npm install apify-client`.
- **Python projects** — the official [Python client](https://docs.apify.com/api/client/python/docs.md): `pip install apify-client`.
- **Any other language** — the [REST API](https://docs.apify.com/api/v2.md).

For usage examples, see the [API](#api) section below.

For more details, see Apify documentation as [Markdown index](https://docs.apify.com/llms.txt) and [Markdown full-text](https://docs.apify.com/llms-full.txt).

# README

## Google Gemini Watermark Checker

**Google Gemini Watermark Checker** takes pasted text or uploaded files and returns structured JSON on whether the writing is **AI generated**. It checks for Google DeepMind **SynthID-Text** — the watermark Google applies to Gemini-generated text — and answers the same question people ask in the Gemini app: *Is this AI generated?* You get `isAiGenerated`, confidence, and a short rationale you can store, alert on, or pipe into a moderation workflow.

![Google Gemini](https://upload.wikimedia.org/wikipedia/commons/thumb/c/c1/Google_%22G%22_logo.svg/200px-Google_%22G%22_logo.svg.png)

***

### What is Google Gemini Watermark Checker?

Google watermarks text produced by Gemini with **SynthID-Text**, an invisible token-probability watermark from DeepMind. You can paste a passage, upload a PDF / Word / text file, and get one dataset row per sample: `isAiGenerated`, `watermarkDetected`, `confidence`, likely source, and token usage.

No login to Google. No browser. Files are converted to text **on the Actor** so the detector only sees the writing — not a 20 MB binary.

***

### What can this Actor do?

- Check **pasted text** or **uploaded files** (PDF, DOCX, TXT, Markdown, HTML, JSON, CSV)
- Return **`isAiGenerated`** plus SynthID-Text / watermark fields in structured JSON
- Sample long files from the **start, middle, and end** instead of sending a whole book
- Cap characters per item so a huge upload cannot silently burn tokens
- Charge **per check** and **per 1,000 input tokens** so large files cost more than a tweet
- Export JSON, CSV, or Excel, or pull results via the Apify API

***

### Why check Gemini text for watermarks?

AI writing is now in essays, support tickets, SEO drafts, and newsroom copy. A watermark check will not replace editorial judgment, but it gives you a **machine-readable signal** you can log next to the document.

Typical jobs:

1. **Newsroom provenance** — flag Gemini-shaped copy before it ships
2. **University integrity** — screen submitted essays and lab reports
3. **Hiring screens** — review cover letters and take-home writeups
4. **SEO / content QA** — catch fully generated blog drafts
5. **Support quality** — see whether macros or Gemini wrote the reply
6. **Legal discovery** — attach an `isAiGenerated` label to produced documents
7. **Brand safety** — scan UGC captions and comments at moderate volume
8. **Dataset labeling** — tag training or evaluation text as AI vs human
9. **Publisher intake** — check freelance submissions
10. **Policy compliance** — EU AI Act-style logging of synthetic text
11. **Education tools** — show students a confidence score, not a verdict
12. **Internal audits** — sample Slack/docs exports for Gemini-heavy writing

***

### How to use Google Gemini Watermark Checker

1. Open the Actor in [Apify Console](https://console.apify.com/)
2. Paste **Text** / **Texts**, or upload **Files**
3. Keep **Max characters per item** at the default unless you know you need a longer sample (you pay for tokens)
4. Click **Start**
5. Download the dataset or read it via the Apify API

#### Input example

```json
{
  "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation...",
  "texts": [
    "In today's rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms..."
  ],
  "files": ["https://example.com/essay.pdf"],
  "maxItems": 5,
  "maxCharsPerItem": 24000
}
```

| Field | Type | Default | Description |
| --- | --- | --- | --- |
| `text` | string | — | One pasted passage |
| `texts` | string\[] | — | Extra pasted passages |
| `files` | string\[] | — | Uploaded file URLs (PDF, DOCX, or text) |
| `maxItems` | integer | `5` | Cap on pasted samples + files this run |
| `maxCharsPerItem` | integer | `24000` | Max characters sent to the detector per item (hard max 100,000) |

***

### Output

Each dataset item is one check. The headline field is **`isAiGenerated`**. `model` is the detector family (`synthid-text`), not a specific chat model.

```json
{
  "id": "a1b2c3d4e5f67890",
  "sourceType": "text",
  "sourceName": "pasted-text-1",
  "sourceUrl": null,
  "textPreview": "Four score and seven years ago...",
  "textLength": 312,
  "wordCount": 58,
  "truncated": false,
  "isAiGenerated": false,
  "watermarkDetected": false,
  "watermarkType": "none",
  "matchesTargetProvider": false,
  "likelySource": "human",
  "likelihood": "low",
  "confidence": 0.86,
  "detectionMethod": "hybrid",
  "rationale": "No SynthID-Text signal; wording matches a well-known human speech.",
  "limitations": null,
  "inputTokens": 912,
  "outputTokens": 180,
  "billedTokenUnits": 1,
  "model": "synthid-text",
  "targetProvider": "google-gemini",
  "error": null,
  "checkedAt": "2026-08-26T12:00:00.000Z"
}
```

***

### Pricing

Long files use more tokens than a tweet. This Actor **passes that cost through with a margin** instead of a flat fee that would lose money on large uploads.

| Event | When | Price (FREE) |
| --- | --- | --- |
| `text-checked` | Once per successful analysis | **$0.005** |
| `input-1k-tokens` | Per **1,000 input tokens** of the sample actually sent (rounded up) | **$0.001** |
| Actor start | Per run (× memory GB) | platform default |

Failed downloads are **not** billed. Failed detector calls are not billed for these events.

**Examples (excluding start fee):**

- \~500-word paste (~800 tokens) → 1 × $0.005 + 1 × $0.001 ≈ **$0.006**
- 24,000-character file sample (~6,000+ tokens with the prompt) → 1 × $0.005 + 7 × $0.001 ≈ **$0.012**

Leave `maxCharsPerItem` at 24,000 unless you have a reason to send more. Raising it toward 100,000 sends more tokens and costs more.

***

### Files and token safety

- Text is **extracted locally** from PDF, DOCX, and text formats. Images, audio, and zip archives are rejected.
- Files over **15 MB** are rejected.
- Longer documents are **sampled** (start / middle / end) up to `maxCharsPerItem`.
- Short samples (under ~50 words) are weak for watermarking — the JSON will say so.

A missing SynthID-Text watermark does **not** prove a human wrote the text. This Actor currently recognizes **Google’s** SynthID-Text key. ChatGPT **text** is not SynthID-watermarked. For ChatGPT **images and audio**, use [OpenAI ChatGPT Watermark Checker](https://apify.com/rainminer/openai-chatgpt-watermark-checker). For Claude-style copy, use [Anthropic Claude Watermark Checker](https://apify.com/rainminer/anthropic-claude-watermark-checker).

***

### Is it legal to check AI-generated text?

This Actor only analyzes content **you provide**. It does not log into anyone’s account. Use it on text you have a right to process, and do not treat the score as legal proof of authorship. Watermarks estimate whether Gemini was involved; they do not identify a person.

***

### Tips

- Prefer **longer passages**. SynthID-Text checks need room to work.
- Upload **text-based PDFs**, not scanned image-only pages (those have no extractable text).
- Watch `billedTokenUnits` in the dataset if a run costs more than you expected.
- Start with `maxItems` 1–3 while you learn the output shape.

***

### Image Credit

Image credit: [Google](https://www.google.com/)

# Actor input Schema

## `text` (type: `string`):

Paste one passage to check. Combine with Texts or Files to check several samples in one run.

## `texts` (type: `array`):

Additional pasted passages. Each item becomes one dataset row.

## `files` (type: `array`):

Upload documents to check. Text is extracted locally from PDF, DOCX, and plain-text files (.txt, .md, .html, .json, .csv) so the detector only sees the writing — not the raw file. Each file is one check. Large files are sampled (start, middle, end) up to Max characters per item.

## `maxItems` (type: `integer`):

Maximum number of pasted samples plus files to analyze in this run. Extra inputs are skipped.

## `maxCharsPerItem` (type: `integer`):

Hard cap on characters sent to the detector for each sample. Longer files are sampled from the start, middle, and end. Keep this modest — you are billed per 1,000 input tokens. Maximum 100,000.

## Actor input object example

```json
{
  "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
  "texts": [
    "In today's rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms can unlock unprecedented value for stakeholders across the ecosystem."
  ],
  "maxItems": 5,
  "maxCharsPerItem": 24000
}
```

# Actor output Schema

## `overview` (type: `string`):

No description

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
const input = {
    "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
    "texts": [
        "In today's rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms can unlock unprecedented value for stakeholders across the ecosystem."
    ],
    "maxItems": 5,
    "maxCharsPerItem": 24000
};

// Run the Actor and wait for it to finish
const run = await client.actor("rainminer/google-gemini-watermark-checker").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_input = {
    "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
    "texts": ["In today's rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms can unlock unprecedented value for stakeholders across the ecosystem."],
    "maxItems": 5,
    "maxCharsPerItem": 24000,
}

# Run the Actor and wait for it to finish
run = client.actor("rainminer/google-gemini-watermark-checker").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print(f"💾 Check your data here: https://console.apify.com/storage/datasets/{run.default_dataset_id}")
for item in client.dataset(run.default_dataset_id).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{
  "text": "Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.",
  "texts": [
    "In today'\''s rapidly evolving digital landscape, it is important to note that leveraging synergistic paradigms can unlock unprecedented value for stakeholders across the ecosystem."
  ],
  "maxItems": 5,
  "maxCharsPerItem": 24000
}' |
apify call rainminer/google-gemini-watermark-checker --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,rainminer/google-gemini-watermark-checker"
        }
    }
}

```

The hosted server signs you in with OAuth on first connect, so no API token belongs in this config. Clients without OAuth support can send an `Authorization: Bearer <APIFY_API_TOKEN>` header instead, using a token from API & Integrations in Apify Console (https://console.apify.com/settings/integrations).

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/MGXkQCIzCdnXj9QZf/builds/0MwF5KUZtFqyUdNoe/openapi.json